A wood plank (length 4.6 m and mass 15.6 kg) is balanced between two saw horses, as shown in the figure below. One saw horse is positioned directly under one end of the plank, and the other is located a distance d1 = 3.4 m away. A child (mass 22 kg) walks along the plank, as if it were a balance beam. What is the furthest distance d2 (in meters) from the end of the plank that the child can walk before the plank tips and falls? Hint: When the plank starts to tip, one of the forces becomes zero.

A meter stick balances horizontally on a knife-edge at the 50.0 cm mark. With two 6.35 g coins stacked over the 11.5 cm mark, the stick is found to balance at the 43.4 cm mark. What is the mass of the meter stick?

A tightrope walker is walking between two buildings holding a pole with length ?=15.5 m, and mass ??=19.5 kg. The daredevil grips the pole with each hand a distance ?=0.575 m from the center of the pole. A bird of mass ??=525 g lands on the very end of the left‑hand side of the pole. Assuming the daredevil applies upward forces with the left and right hands in a direction perpendicular to the pole, what magnitude of force ?left and ?right must the left and right hand exert to counteract the torque of the bird?

The uniform seesaw shown below is balanced on a fulcrum located d1 = 3.5m from the left end. The bigger boy on the left end has a mass m1 =75 kg. The smaller boy on the right end has a mass of m2 = 55 kg and is a distance d2 = 4.5 m from the fulcrum. The mass of the board is mb.    Draw all forces acting on the seesaw board showing their directions and locations. Where would you draw the weight of the board? Identify and show the direction of rotations caused by the torques provided by all forces about the fulcrum. If the seesaw is in static equilibrium, write down the two conditions of static equilibrium symbolically using the forces and distances in the figure. Solve for the mass of the board. Calculate the force of fulcrum on the board.